Patent Literature 1 discloses a fluoroelastomer vulcanizing composition characterized in that it comprises (a) a peroxide vulcanizable fluoroelastomer, (b) an organic peroxide, (c) a multi-functional co-crosslinking agent and (d) a phenolic antioxidant which contains per molecule 1 to 4 hydroxyphenyl groups having 1 or 2 tert-butyl groups. It also discloses that sealing components such as O-rings formed with the fluoroelastomer vulcanizing composition have significantly improved heat and aging resistance and sealing performance at high temperatures, so that they can retain the sealing performance for a prolonged period of time.
Known fluoroelastomers include, in addition to the peroxide vulcanizable fluoroelastomer disclosed in Patent Literature 1, polyol-crosslinkable fluoroelastomers. The polyol-crosslinkable fluoroelastomers are applied to many fields because of their small compression set and superior moldability among other fluoroelastomers.
Quaternary onium salts such as quaternary phosphonium salts and quaternary ammonium salts are used as vulcanization accelerators for polyol-crosslinking.